1. Field of the Invention
The present invention relates to a bellows cylinder used for a vehicular suspension and other general machinery and others.
2. Description of the Related Art
Heretofore, a bellows cylinder is greatly used for the extension part of machinery and others. For example, a bump cushion (also called a bump stopper and a cushion rubber) 55 is attached to the upper part of a piston rod 51 of an oil cushion 50 as shown in FIG. 12 in a suspension provided to the front wheel or the rear wheel of a vehicle, a bellows cylinder 61 consisting of an elastic body such as rubber for covering the piston rod 51 and the bump cushion 55 is attached and a coil spring 65 may be also attached outside the bellows cylinder 61. A reference number 52 denotes a cylinder, 67 denotes an upper spring seat, 68 denotes a lower spring seat and 69 denotes a metallic cylindrical reinforcement. The above bellows cylinder 61 used for a vehicular suspension is normally called a dust cover, however, in this specification, it is called a bellows cylinder.
In the suspension, the piston rod 51 and the coil spring 65 of a shock absorber are stretched or contracted against vibration and shock from a road surface to absorb shock, when they are compressed at their maximum, the upper end of the cylinder 52 is in contact with the bump cushion 55 and the compression and transformation of the bump cushion 55 prevent the upper end of the cylinder from coming in contact with the bottom. The above bellows cylinder 61 is stretched or contracted together with the piston rod 51 and the coil spring 65 to prevent mud from adhering to the piston rod 51 and the bump cushion 55 and a stone on a road surface from hitting on them.
The length of the above piston rod 51 and others is different depending upon the type of a vehicle, whether a suspension is for a front wheel or a rear wheel and others and according to the length, the length of the bellows cylinder 61 is also different. Therefore, if the bellows cylinder 61 is long as in this example, a part of bellows 62 is bent (hereinafter called the bend of the barrel) in the radial direction on the way of compression as shown in FIG. 13 and may come in contact with the coil spring 65 and the cylinder 52. The part of bellows 62 may be damaged by contact with the coil spring 65 and others.
It can be considered that to prevent the barrel of the bellows cylinder 61 from being bent, the diameter of the bellows cylinder 61 is extended, however, as the coil spring 65 surrounds the outside of the bellows cylinder 61, there is a limit to the diameter of the bellows cylinder 61. Thus, the diameter cannot be extended enough to prevent the barrel from being bent when the bellows cylinder is compressed. In addition, as the diameter of the coil spring 65 is determined in view of a function and space, the diameter of the coil spring 65 cannot be also changed to extend the diameter of the bellows cylinder 61.